Wave-detector for wireless telegraphy.



W. SUHLOEMILCH & P. P. PICHON.

WAVE DETECTOR FOR WIRELESS TELEGRAPHY. APPLIGATIONTILED APR 14. 1906.

962,262. Patented June 21,1910.

I Mandi UNITED STATES PATENT OFFICE.

WILHELM SCHLOEMILCH, or BERLIN, A D PAUL FERNAND} PIGHON, or sfinnNnn',

NEARBERLIN, GERMANY, ASSIGNORS 'ro GESELLSCHAFT run DRAHTLOSE TELE-GRAPHIE m. :B. 11., 0F BERLIN, GERMANY. H

WAVE-DETECTOR FOR WIRELESS TELEGRAPHY.

Application filed April 14, 1906. Serial No. 311,678. I I

To all whom it may concern:

Be it known that we, WILHELM SCHLOE- MILcH, a sub ect of the King ofPrussia, re-

. drawing, forming a part of this specification.

This invention relates to detectors such as are employed in wirelesstelegraphy for indicating the presence of electric waves, and moreparticularly to those detectors which are formed of one or more contactssensitive to wave action. To this classbelongs the ordinary coherer andalso the microphonic contact which is'generally; formed. of twoconductors of the first class which contact each other with slightpressure. This contact pressure is. very small; in the detectorshitherto employed of this kind, so that even very smallvibrations-yvhich are unavoidable during w0rking, suflice to alter thecontact, which of course gives rise to disagreeable interruptions inworkin If in the contacts hithertoknown a hi er pres sure be employedwhich renders. tiem 1ndependent .ofexternal 'vibrations, they lose theproperty of. being sensitive to waves. Now this invention relates to awave-sensitivecontact which, owing to'the use ofcertain materialsfor thecontact. elements, permitsthe use of a high contact pressure withoutlosing its sensitivene'ss to waves. On the contrary it hasbeen foundthat the wave sensitiveness where such materials areiusedcomes outparticularly favorable only at higher pressures at which the knowncontacts entirely lose their effect. The materialswhich. exhibit thesaid. properties are the, naturally exist ing manganese compounds,asm'ay be ascertamed by experimentafor instance, ps'ilomelane(barytiferous oxid of manganese), pyrolusite (peroxid of manganese),braunite (sesquioxid of manganese),manganite (hydrous-oxid of manganese)and others, in contradistinction to chemicall' ure com. pounds, such asmanganese an t e binoxid of manganese previously roposedfor thispurpose. The reason wfy the naturally found compounds have the desiredproperty andnot the chemically pure com ounds is supposed to be that thenatura y i found compounds have moisture either chemically ormechanically combined with them. These materials may be employed foreither both contacts or only one. It is, however, preferable to form oneof the contact bodies of a good conducting material, preferably of amaterial which does ,not oxidize or only oxidizes with difliculty, forinstance, plati: num, gold, silver, aluminiumand even lead arefound tobe very advantageous. In the accompanying drawings: Figure 1 shows aform ofconstruction ofthe wave sensitive contact piece. Fig. 2 shows arejceiver connectionsin which the detector works with an auxiliarysource of potential, and Fig. 3 a receiver connection'ln. whichtheldetector works without auxiliary potentia I I -,In Fig. 1, 1indicates a piece of psilom'e- Ian which is preferably embedded in tin 2which is surrounded with abrass 'sheath or socket 3. Against the uppersurface of the psilomelan a platinum pin,5 soldered to a screw lstrongly presses. ranged in a vulcanite plug 6 which inturn isdisplat-eably held by-meansiof screw thread in the brass sheath orsocket 3. On the upper end of theviilcaniteyplug 61a metal plate 7' isattached by means of screws ter, the comparatively high'pressur'e of theelectrodes one upon, the other, may. be easily kept constant. ,The form,and size of the contact'surfaees of both bodies-according to the choiceof the same have also been.

found to be of im ortance for '-obtaining favorable action, I forinstance,.psilom elaneand platinum beemployed it is preferable cause theplatinum to act' in the form The screw is -arand a'short conductor8establishes an elecof a pencil on a polished surface of the psilomelane.If, in place of the platinum,

lead be employed this is preferably used in the form of a large platewhich is pressed with great pressure against the psilomelane.

The connection of this improved detector with the circuits for wirelesstelegraphy may be made in the same way as the connection of the ordinarydetectors at present employed for similar objects such, for instance, ascoherers, electrolytic cells or microphone contacts. A method ofconnecting up the mproved detector is shown as an example in-Fig. 2. Thereceiver circuit is here composed of an aerial wire 9, rimarytransformer coil 10, variable sel -induction coil 11, an adjustablecondenser 12, and a connecting Wire 13 carried to earth or to anequivalent. The detector circuit is inductively coupled with thereceiver circuit, and also, contains in addition to the secondary coil14, the adjustable condenser 15, and wave sensitive contact 1, 5, inconnection wlth which an adjustable condenser 16 is inserted inparallel. The wave sensitive contact is connected over choking coils 17with the potentiometer 18, which serves for producing the necessarypotential at the electrodes of the wave sensitive contact. Anequalization of the potentiometer 0 tential over the coil 14 isprevented by thecondenser 15. 19 indicates an energy indicator(telephone, galvanometer or the like) for enabling the alterations..,which take place in the detector undertlie influence of the electricwaves to be ascertained. The coupling of the receiver circuit with thedetector circuit may of course instead of being-inductive also be madeconductive.

The auxiliary potential to be impressed upon the wave sensitive contact1, 5, varies according to the kind of material employed and is alsodependent on the shape and kind of contact surface. Thus it is notpossible to fix a given referable value for the auxiliary potentia to beemployed. This for psilomelan is about 1 volt, if it be desired toobtain a maximum sensitiveness with the.

smallest amount'of sound in the telephone. If it be intendedtoincrease'the maximum strength of the sound,'it is necessa to increasethe auxiliary potential, whereby how In using tained by having apermanent current of about one to two milliamperes flowing through thewave sensitive contact 'part. The

The physical properties of the bodies found to be effective to bringabout the improved actionhave not hitherto been ascertained. As regardsthis, it may be pointed out that all hitherto discovered naturally foundmanganese compounds contain to a high extent moisture or waterchemically or mechanically combined. It has not been pos sible up to thepresent to discover whether the improved action is perhaps to beascribed to these properties of the bodies alone, or not. Havingexplained our invention, what we do claim and desire to secure byLetters Patent is:

1. A wave detector for wireless telegraphy, consisting of two contactbodies, one I of which is formed of one of the naturally .foundmanganese compounds containing moisture.

2. A wave detector for Wireless telegraphy, consisting of two contactbodies, one of which ,is formed of one ofthe naturally found manganesecompounds containing moisture, and the other of a material whichoxidizes with difficulty.

3. A wave detector for wireless telegraphy, consisting of two contactbodies, one of which is formed of one of the naturally found manganesecompounds containing moisture, and thepther of a material which oxidizeswith diificulty, said contacts touch- M ing each other withapredetermined pressure. I

4. A wave detector for wireless telegraphy consisting of two contactingbodies, one of which is .formed of psilomelane.

In witness whereof, we hereunto subscribe our names this 31st day ofMarch A. D. 1906.

' WILHELM SCHLOEMILCH.

PAUL FERNAND PICHON. Witnesses:

Wonnnu.m Ham, Hnxizr Harlin.

